WASHINGTON STATE
BUILDING CODE
CHAPTER 51-51 WAC
INTERNATIONAL RESIDENTIAL CODE 2012 Edition
Washington State Building Code Council
Effective July 1, 2013
Copies of the State Building Codes and
complete copies of the 2012 International Residential Code
as published by the International Code Council
may be obtained from:
Washington Association of Building Officials
Post Office Box 7310
Olympia, Washington 98507-7310
(360) 628-8669 www.wabobookstore.org
or toll free in Washington State at (888) 664-9515
The 2012 International Residential Code,
as published by the International Code Council,
may be viewed at the following website:
http://publicecodes.cyberregs.com/icod/irc/index.htm
First Edition
International Residential Code
Chapter 51-51 WAC
Effective July 1, 2013
Fifth Edition based on
WSR 13-04-068
i
Preface Authority: The International Residential Code (Chapter 51-51 WAC) is adopted by the Washington State Building Code
Council pursuant to Chapters 19.27 and 70.92 RCW. These codes were first adopted by reference by the Washington State
Legislature in 1974. In 1985, the Legislature delegated the responsibility of adoption and amendment of these codes to the State
Building Code Council.
Code Precedence: The State Building Code Act, Chapter 19.27 RCW, establishes the following order of precedence among the
documents adopted as parts of the State Building Code:
International Building Code, Standards and amendments -WAC 51-50;
International Residential Code, Standards and amendments – WAC 51-51;
International Mechanical Code, Standards and amendments - WAC 51-52;
International Fire Code, Standards and amendments - WAC 51-54;
Uniform Plumbing Code, Standards and amendments - WAC 51-56
Where there is a conflict between codes, an earlier named code takes precedence over a later named code. In the case of conflict
between the duct insulation requirements of the International Mechanical Code and the duct insulation requirements of the
Energy Code, the Energy Code, or where applicable, a local jurisdiction's energy code, shall govern.
Where, in any specific case, different sections of this Code specify different materials, methods of construction or other
requirements, the most restrictive shall govern. Where there is conflict between a general requirement and a specific requirement,
the specific requirement shall be applicable.
Organization and Numbering: These rules are written to allow compatible use with the International Residential Code. All
sections which are amended, deleted, or added are referenced.
Enforcement: The State Building Code Act requires that each local jurisdiction enforce the State Building Code within its
jurisdiction. Any jurisdiction can contract with another jurisdiction or an inspection agency to provide the mandated enforcement
activities.
Amendments to the State Building Code:
The State Building Code Council has adopted review procedures and approval criteria for local amendments. These
procedures and criteria are found in Chapter 51-04 WAC. The Council has exempted from its review any amendments
to the administrative provisions of the various codes.
Forms for proposing statewide amendments to the State Building Code are available from the State Building Code
Council staff.
A. Amendments of Statewide Application: On a yearly basis the State Building Code Council will consider
proposals to amend the State Building Code. Unless directed by the State Legislature, federal mandates or court
order, the Council will not enter formal rulemaking until 2015 as part of its consideration of adoption of the 2015
series of codes.
Proposals to amend the State Building Code shall be made on forms provided by the Building Code Council.
Code Change Proposal Submittal Deadline: March 1st of each year.
B. Local Amendments: Any jurisdiction may amend the State Building Code provided the amendments do not reduce
the minimum performance standards of the codes. There are areas where local amendments are limited or
prohibited:
ii
Prohibited Amendments: Residential provisions of the State Energy Code (WAC 51-11R and 51-11C), Ventilation
provisions in Section 408 of the Mechanical Code (WAC 51-52) and Section M1507.3 of the IRC (WAC 51-51); any
provision of the International Building Code or International Residential Code affecting accessibility; and standards
specifically adopted in Chapters 19.27 and 19.27A RCW cannot be amended by any local jurisdiction.
Residential Amendments: Amendments by local jurisdictions which affect the construction of single family
and multi-family residential buildings must be reviewed and approved by the State Building Code Council
before such amendments can be enforced. The State Building Code Act provides the following definition:
―Multi-family residential building‖ means common wall residential buildings that consist of four
or fewer units, that do not exceed two stories in height, that are less than 5,000 square feet in area,
and that have a one-hour fire-resistive occupancy separation between units.
Application forms for Council review of local amendments are available from the State Building Code Council Staff.
Washington State Building Code Council
Post Office Box 41449
Olympia, Washington 98504-1449
www.sbcc.wa.gov
(360) 407-9280 Fax (360) 586-9088
e-mail: [email protected]
Printing Format: This version of the rules is published as a series of insert or replacement pages. Each page provides
instructions for installing them in the model code book. Amendments to the model code which are new or revised from
the previous edition of this code are indicated by a line in the margin next to the revised portions.
Effective Date: These rules were adopted by the State Building Code Council on November 9, 2012. The rules are
effective throughout the state on July 1, 2013. (This version of the code is based on WAC 51-51 as published in WSR
13-04-068. It is subject to review by the State Legislature during the 2013 session.)
Building Permit Fees: The activities of the State Building Code Council are supported by permit fees collected by each
city and county. Section 19.27.085 of the State Building Code Act requires that a fee of $4.50 be imposed on each
building permit issued by each city and county. In addition, a fee of $2.00 per unit shall be imposed for each dwelling
unit after the first unit, on each building containing more than one residential unit. For the purpose of this fee, WAC
365-110-035 defines building permits as any permit to construct, enlarge, alter, repair, move, improve, remove, convert
or demolish any building or structure regulated by the Building Code. Exempt from the fee are plumbing, electrical,
mechanical permits, permits issued to install a mobile/manufactured home, commercial coach or factory built structure,
or permits issued pursuant to the International Fire Code.
Each city and county shall remit moneys collected to the state treasury quarterly. No remittance is required until a
minimum of $50.00 has accumulated.
These permit fees are the amounts current in January 2013. Such fees may be changed by the State Legislature.
Opinions: Only at the request of local enforcement official, the State Building Code Council may issue
interpretations/opinions of those provisions of the State Building Code created by the Council, or provisions of the model
codes amended by the Council. Final interpretation authority for any specific permit resides with the local enforcement
official.
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Table of Contents
Section Page
WAC 51-51-001 Authority ........................................................................................ A
WAC 51-51-002 Purpose ........................................................................................... A
WAC 51-51-003 International Residential Code ..................................................... A
WAC 51-51-007 Exceptions ....................................................................................... A
WAC 51-51-008 Implementation .............................................................................. A
WAC 51-51-0100 Chapter 1 Administration
Section 102 – Applicability ............................................................. 1
WAC 51-51-0200 Chapter 2 Definitions
Section 202 – Definitions ................................................................ 11
WAC 51-51-0300 Chapter 3 Building Planning
Section 301 – Design Criteria .......................................................... 46
Section 302 – Exterior Wall Location ............................................. 48
Section 303 – Light, Ventilation and Heating ................................. 53
Section 311 – Means of Egress ........................................................ 60
Section 313 – Automatic Fire Sprinkler Systems ............................ 62
Section 314 – Smoke Alarms .......................................................... 63
Section 315 – Carbon Monoxide Alarms ........................................ 63
Section 322 – Flood Resistant Construction ..................................... 69
Section 325 – Adult Family Homes ................................................. 71
Section 326 – Family Child Day Care Homes ................................. 71a
Section 327 – Protection Against Radon ......................................... 71b
Section 328 – Mezzanines ............................................................... 71b
WAC 51-51-0400 Chapter 4 Foundations
Section 403 – Footings .................................................................... 78
Section 404 – Foundation and Retaining Walls ............................... 96
Section 408 – Under Floor Space .................................................... 111
WAC 51-51-0500 Chapter 5 Floors
Section 501 – General ...................................................................... 113
Section 507 – Decks ........................................................................ 146
WAC 51-51-0600 Chapter 6 Wall Construction
Section 602 – Wood Wall Framing ................................................. 158
Section 612 – Exterior Windows and Doors ................................... 347
WAC 51-51-0700 Chapter 7 Wall Covering
Section 702 – Interior Covering ....................................................... 362
Section 703 – Exterior Covering ..................................................... 363
iv
WAC 51-51-0900 Chapter 9 Roof Assemblies
Section 903 – Weather Protection .................................................... 439
WAC 51-51-1000 Chapter 10 Chimneys and Fireplaces
Section 1001 – Masonry Fireplaces .................................................. 453
Section 1002 – Masonry Heaters ...................................................... 457
Section 1004 – Factory-Built Fireplaces .......................................... 461
Section 1006 – Exterior Air Supply ................................................. 462
Chapter 11 is not adopted
WAC 51-51-1200 Chapter 12 Mechanical Administration
Section 1201 – General ..................................................................... 493
WAC 51-51-1300 Chapter 13 General Mechanical System Regulations
Section 1301 – General ..................................................................... 495
WAC 51-51-1500 Chapter 15 Exhaust Systems
Section 1507 – Mechanical Ventilation ............................................ 508
WAC 51-51-1600 Chapter 16 Duct Systems
Section 1601 – Duct Construction .................................................... 511
WAC 51-51-1700 Chapter 17 Combustion Air
Section 1701 – General ..................................................................... 515
WAC 51-51-2000 Chapter 20 Boilers and Water Heaters
Section 2001 – Boilers ...................................................................... 523
Chapters 25 through 42 are not adopted
WAC 51-51-4400 Chapter 44 Referenced Standards ................................................ 781
WAC 51-51-60000 Appendix F Radon Control Methods
Section AF103 – Requirements ........................................................ 821
WAC 51-51-60105 Appendix R Dwelling Unit Fire Sprinkler Systems .................... 890a
WAC 51-51-60107 Appendix S Fire Sprinklers .......................................................... 890b
WASHINGTON STATE AMENDMENTS
Effective July 1, 2013
CHAPTER 51-51 WAC STATE BUILDING CODE ADOPTION AND AMENDMENT
OF THE 2012 EDITION OF THE INTERNATIONAL RESIDENTIAL CODE
WAC 51-51-001 AUTHORITY
These rules are adopted under the authority of Chapter
19.27 RCW.
WAC 51-51-002 PURPOSE
The purpose of these rules is to implement the provisions
of Chapter 19.27 RCW, which provides that the State
Building Code Council shall maintain the State Building
Code in a status which is consistent with the purpose as set
forth in RCW 19.27.020. In maintaining the codes the
Council shall regularly review updated versions of the
codes adopted under the act, and other pertinent
information, and shall amend the codes as deemed
appropriate by the Council.
WAC 51-51-003 INTERNATIONAL RESIDENTIAL CODE
The 2012 edition of the International Residential Code as
published by the International Code Council is hereby
adopted by reference with the following additions, deletions
and exceptions: Provided that chapters 11 and 25 through
43 of this code are not adopted. The Energy Code is
regulated by chapter 51-11R WAC; the Plumbing Code is
regulated by chapters 51-56 WAC; the Electrical Code is
regulated by chapter 296-46B WAC or the Electrical Code
as adopted by the local jurisdiction. Appendix F, Radon
Control Methods; Appendix G, Swimming Pools, Spas and
Hot Tubs; and Appendix R, Dwelling Unit Fire Sprinkler
Systems, are included in adoption of the International
Residential Code.
WAC 51-51-007 EXCEPTIONS
The exceptions and amendments to the International
Residential Code contained in the provisions of Chapter
19.27 RCW shall apply in case of conflict with any of the
provisions of these rules.
The provisions of this code do not apply to temporary
growing structures used solely for the commercial
production of horticultural plants including ornamental
plants, flowers, vegetables, and fruits. ―Temporary
growing structure‖ means a structure that has the sides and
roof covered with polyethylene, polyvinyl, or similar
flexible synthetic material and is used to provide plants
with either frost protection or increased heat retention. A
temporary growing structure is not considered a building
for purposes of this code.
The provisions of this code do not apply to the
construction, alteration, or repair of temporary worker
housing except as provided by rule adopted under chapter
70.114A RCW or chapter 37, Laws of 1998 (SB 6168).
"Temporary worker housing" means a place, area, or piece
of land where sleeping places or housing sites are provided
by an employer for his or her employees or by another
person, including a temporary worker housing operator,
who is providing such accommodations for employees, for
temporary, seasonal occupancy, and includes "labor camps"
under RCW 70.54.110.
Codes referenced which are not adopted through RCW
19.27.031 or RCW 19.27A shall not apply unless
specifically adopted by the authority having jurisdiction.
The standards for liquefied petroleum gas installations
shall be NFPA 58 (Liquefied Petroleum Gas Code) and
NFPA 54 (National Fuel Gas Code). All other fuel gas
installations shall be regulated by the International
Mechanical Code and International Fuel Gas Code.
WAC 51-51-008 IMPLEMENTATION
The International Residential Code adopted under
Chapter 51-51 WAC shall become effective in all counties
and cities of this state on July 1, 2013.
A
2012 INTERNATIONAL RESIDENTIAL CODE
Effective July 1, 2013
(Insert Facing Page 1)
R102.5 Appendices. Provisions in the appendices shall not
apply unless specifically referenced in the adopting
ordinance. Except for Appendix S, Fire Sprinklers, an
appendix adopted by a local jurisdiction shall not be effective
unless approved by the State Building Code Council pursuant
to RCW 19.27.060(1)(a). The State Building Code Council has
determined that a local ordinance requiring fire sprinklers in
accordance with Appendix S of this chapter may be adopted by
any local government upon notification of the Council.
Appendix F, Radon Control Methods, G, Swimming Pools,
Spas and Hot Tubs, and Appendix R, Dwelling Unit Fire
Sprinkler Systems, are included in adoption of the
International Residential Code.
R102.7.1 Additions, alterations or repairs. Additions,
alterations or repairs to any structure shall conform to the
requirements for a new structure without requiring the
existing structure to comply with all of the requirements of
this code, unless otherwise stated. Additions, alterations or
repairs shall not cause an existing structure to become
unsafe or adversely affect the performance of the building.
Exceptions:
1. Additions with less than 500 square feet of
conditioned floor area are exempt from the
requirements for Whole House Ventilation Systems,
Section M1508.
2. Additions or alterations to existing buildings which
do not require the construction of foundations,
crawlspaces, slabs or basements shall not be required
to meet the requirements for radon protection in
Section R327.1 and Appendix F.
R102.7.2 Moved Buildings. Buildings or structures moved
into or within a jurisdiction shall comply with the provisions
of this code, the International Building Code (WAC 51-50),
the International Mechanical Code (WAC 51-52), the
International Fire Code (WAC 51-54), the Uniform
Plumbing Code and Standards (WAC 51-56), and the
Washington State Energy Code (WAC 51-11R) for new
buildings or structures.
Exception: Group R-3 buildings or structures are not
required to comply if:
1. The original occupancy classification is not
changed; and
2. The original building is not substantially
remodeled or rehabilitated.
For the purposes of this section a building shall be
considered to be substantially remodeled when the costs of
remodeling exceed 60 percent of the value of the building
exclusive of the costs relating to preparation, construction,
demolition or renovation of foundations.
WASHINGTON STATE AMENDMENTS
Effective July 1, 2013
2012 INTERNATIONAL RESIDENTIAL CODE
Effective July 1, 2013
ADULT FAMILY HOME means a dwelling in which a
person or persons provide personal care, special care, room
and board to more than one but not more than six adults
who are not related by blood or marriage to the person or
persons providing the services.
(Insert Facing Page 11)
WASHINGTON STATE AMENDMENTS
Effective July 1, 2013
ATTIC, HABITABLE. A conditioned area complying with all
of the following requirements:
1. The occupiable floor area is at least 70 square feet
(6.5 m2), in accordance with Section R304,
2. The occupiable floor area has a ceiling height in
accordance with Section R305, and
3. The occupiable space is entirely enclosed by the roof
assembly above, knee walls (if applicable) on the
sides, and the floor-ceiling assembly below.
A habitable attic is not considered a story,
(Insert Facing Page 12)
2012 INTERNATIONAL RESIDENTIAL CODE
Effective July 1, 2013
CHILD DAY CARE, shall, for the purposes of these
regulations, mean the care of children during any period of
a 24 hour day.
CHILD DAY, FAMILY HOME. A child care facility,
licensed by Washington state, located in the dwelling of the
person or persons under whose direct care and supervision
the child is placed, for the care of twelve or fewer children,
including children who reside at the home.
(Insert Facing Page 13)
WASHINGTON STATE AMENDMENTS
Effective July 1, 2013
2012 INTERNATIONAL RESIDENTIAL CODE
Effective July 1, 2013
DWELLING UNIT. A single unit providing complete
independent living facilities for one or more persons,
including permanent provisions for living, sleeping, eating,
cooking and sanitation. Dwelling units may also include the
following uses:
1. Adult family homes, foster family care homes and
family child day care homes licensed by the
Washington state department of social and health
services.
2. Offices, mercantile, food preparation for off-site
consumption, personal care salons or similar uses
which are conducted primarily by the occupants of
the dwelling unit and are secondary to the use of the
unit for dwelling purposes, and which do not exceed
500 square feet (46.4m2).
3. One accessory dwelling unit, which need not be
considered a separated dwelling unit, provided:
a. The accessory dwelling unit is constructed
within an existing dwelling unit.
b. Either the accessory dwelling unit or primary
dwelling unit is owner-occupied.
c. All required smoke alarms in the accessory
dwelling unit and the primary dwelling unit are
interconnected in such a manner that the
actuation of one alarm will activate all alarms in
both the primary dwelling unit and the accessory
dwelling unit.
(Insert Facing Page 15)
WASHINGTON STATE AMENDMENTS
Effective July 1, 2013
FIRE SEPARATION DISTANCE. The distance
measured from the foundation wall or face of the wall
framing, whichever is closer, to one of the following:
1. To the closest interior lot line; or
2. To the centerline of a street, an alley or public way;
or
3. To an imaginary line between two buildings on the
lot.
The distance shall be measured at a right angle from the
wall.
(Insert Facing Page 16)
2012 INTERNATIONAL RESIDENTIAL CODE
Effective July 1, 2013
WASHINGTON STATE AMENDMENTS
Effective July 1, 2013
2012 INTERNATIONAL RESIDENTIAL CODE
Effective July 1, 2013
(Insert Facing Page 19)
MEZZANINE, LOFT. An intermediate level or levels
between the floor and ceiling of any story.
WASHINGTON STATE AMENDMENTS
Effective July 1, 2013
SMALL BUSINESS. Any business entity (including a sole
proprietorship, corporation, partnership or other legal
entity) which is owned and operated independently from all
other businesses, which has the purpose of making a profit,
and which has fifty or fewer employees.
(Insert Facing Page 22)
2012 INTERNATIONAL RESIDENTIAL CODE
Effective July 1, 2013
WASHINGTON STATE AMENDMENTS
Effective July 1, 2013
WHOLE HOUSE VENTILATION SYSTEM. A mechanical
ventilation system, including fans, controls, and ducts,
which replaces, by direct or indirect means, air from the
habitable rooms with outdoor air.
(Insert Facing Page 24)
2012 INTERNATIONAL RESIDENTIAL CODE
Effective July 1, 2013
WASHINGTON STATE AMENDMENTS
Effective July 1, 2013
R301.2.2.3.1 Height limitations. Wood-framed buildings
shall be limited to three stories above grade plane or the
limits given in Table R602.10.3(3). Cold-formed, steel-
framed buildings shall be limited to less than or equal to
three stories above grade plane in accordance with AISI
S230. Mezzanines that comply with Section R328 shall not
be considered as stories. Structural insulated panel
buildings shall be limited to two stories above grade plane.
(Insert Facing Page 46)
2012 INTERNATIONAL RESIDENTIAL CODE
Effective July 1, 2013
WASHINGTON STATE AMENDMENTS
Effective July 1, 2013
R302.2.1 Continuity. The fire-resistance-rated wall or
assembly separating townhouses shall be continuous from
the foundation to the underside of the roof sheathing, deck
or slab. The fire-resistance rating shall extend the full
length of the wall or assembly, including wall extensions
through and separating attached enclosed accessory
structures.
Where a story extends beyond the exterior wall of a story
below:
1. The fire-resistance-rated wall or assembly shall
extend to the outside edge of the upper story; or
2. The underside of the exposed floor-ceiling assembly
shall be protected as required for projections in
Section R302.
TABLE R302.1(1) EXTERIOR WALLS
EXTERIOR WALL ELEMENT MINIMUM
FIRE-RESISTANCE RATING MINIMUM FIRE
SEPARATION DISTANCE
Walls (Fire-resistance rated)
1-hour tested in accordance with ASTM E 119
or UL 263 with exposure from both sides < 5 feet
(Not fire-resistance rated) 0 hours ≥ 5 feet
Projections (Fire-resistance rated) 1 hour on the underside
a,b ≥ 2 feet to < 5 feet
(Not fire-resistance rated) 0 hours ≥ 5 feet
Openings in walls
Not allowed N/A < 3 feet
25% maximum of
wall area per story 0 hours 3 feet
Unlimited 0 hours 5 feet
Penetrations All Comply with Section R302.4 < 5 feet
None required 5 feet For IS: 1 foot = 304.8 mm. N/A = Not Applicable
a. Roof eave fire-resistance rating shall be permitted to be reduced to 0 hours on the underside of the eave if fire blocking is provided from the
wall top plate to the underside of the roof sheathing.
b. Roof eave fire-resistance rating shall be permitted to be reduced to 0 hours on the underside of the eave provided no gable vent openings are
installed.
(Insert Facing Page 48)
2012 INTERNATIONAL RESIDENTIAL CODE
Effective July 1, 2013
R302.2.4 Structural independence. Each individual
townhouse shall be structurally independent.
Exceptions:
1. Foundation supporting exterior walls or common
walls.
2. Structural roof and wall sheathing from each unit may
be fastened to the common wall framing.
3 Nonstructural wall and roof coverings.
4. Flashing at termination of roof covering over common
wall.
5. Townhouses separated by a common 2-hour fire-
resistance-rated wall as provided in Section R302.2.
6. Floor sheathing may fasten to the floor framing of
both units.
TABLE R302.1(2) EXTERIOR WALLS – DWELLINGS WITH FIRE SPRINKLERS
EXTERIOR WALL ELEMENT MINIMUM
FIRE-RESISTANCE RATING MINIMUM FIRE
SEPARATION DISTANCE
Walls (Fire-resistance rated)
1-hour tested in accordance with ASTM E 119
or UL 263 with exposure from both sides 0 feet
(Not fire-resistance rated) 0 hours 3 feeta
Projections (Fire-resistance rated) 1 hour on the underside
b,c 2 feet
a
(Not fire-resistance rated) 0 hours 3 feet
Openings in walls Not allowed N/A < 3 feet
Unlimited 0 hours 3 feeta
Penetrations All Comply with Section R302.4 < 3 feet
None required 3 feeta
For IS: 1 foot = 304.8 mm. N/A = Not Applicable
a. For residential subdivisions where all dwellings are equipped throughout with an automatic sprinkler system installed in accordance with
P2904, the fire separation distance for nonrated exterior walls and rated projections shall be permitted to be reduced to 0 feet, and
unlimited unprotected openings and penetrations shall be permitted, where the adjoining lot provides an open setback yard that is 6 feet or
more in width on the opposite side of the property line.
b. Roof eave fire-resistance rating shall be permitted to be reduced to 0 hours on the underside of the eave if fire blocking is provided from
the wall top plate to the underside of the roof sheathing.
c. Roof eave fire-resistance rating shall be permitted to be reduced to 0 hours on the underside of the eave provided no gable vent openings
are installed.
(Insert Facing Page 49)
WASHINGTON STATE AMENDMENTS
Effective July 1, 2013
2012 INTERNATIONAL RESIDENTIAL CODE
Effective July 1, 2013
R303.1 Natural Light. All habitable rooms shall have an
aggregate glazing area of not less than 8 percent of the floor
area of such rooms.
Exception: The glazed areas need not be installed in rooms
where artificial light is provided capable of producing an
average illumination of 6 footcandles (65 lux) over the area
of the room at a height of 30 inches (762 mm) above the
floor level.
R303.2 Adjoining Rooms. For the purpose of determining
light requirements, any room shall be considered as a
portion of an adjoining room when at least one-half of the
area of the common wall is open and unobstructed and
provides an opening of not less than one-tenth of the floor
area of the interior room but not less than 25 square feet
(2.3 m2).
Exception: Openings required for light shall be permitted to
open into a thermally isolated sunroom addition or patio
cover, provided that there is an openable area between the
adjoining room and the sunroom addition or patio cover of
not less than one-tenth of the floor area of the interior room
but not less than 20 square feet (2 m2).
R303.3 Bathrooms. This section is not adopted. (Insert Facing Page 53)
R303.4 Minimum ventilation performance. Dwelling
units shall be equipped with local exhaust and whole house
ventilation systems designed and installed as specified in
Section M1507.
Exception: Additions with less than 500 square feet of
conditioned floor area are exempt from the requirements in
this code for Whole House Ventilation Systems.
R303.5.2 Exhaust openings. Exhaust air shall not be
directed onto walkways. All exhaust ducts shall terminate
outside the building. Terminal elements shall have at least
the equivalent net free area of the duct work.
R303.5.2.1 Exhaust ducts. Exhaust ducts shall be
equipped with back-draft dampers. All exhaust ducts in
unconditioned spaces shall be insulated to a minimum of
R-4.
R303.7 Stairway Illumination. All interior and exterior
stairways shall be provided with a means to illuminate the
stairs, including the landings and treads. Stairway
illumination shall receive primary power from the building
wiring. Interior stairways shall be provided with an
artificial light source located in the immediate vicinity of
each landing of the stairway. For interior stairs the artificial
light sources shall be capable of illuminating treads and
landings to levels not less than 1 foot-candle (11 lux)
measured at the center of treads and landings. Exterior
stairways shall be provided with an artificial light source
located in the immediate vicinity of the top landing of the
stairway. Exterior stairways providing access to a basement
from the outside grade level shall be provided with an
artificial light source located in the immediate vicinity of
the bottom landing of the stairway.
Exception: An artificial light source is not required at
the top and bottom landing, provided an artificial light
source is located directly over each stairway section.
WASHINGTON STATE AMENDMENTS
Effective July 1, 2013
R303.9 Required heating. When the winter design
temperature in Table R301.2(1) is below 60°F (16°C), every
dwelling unit shall be provided with heating facilities capable
of maintaining a minimum room temperature of 68°F (20°C) at
a point 3 feet (914 mm) above the floor and 2 feet (610 mm)
from exterior walls in all habitable rooms at design
temperature. The installation of one or more portable heaters
shall not be used to achieve compliance with this section.
Exception: Unheated recreational tents or yurts not
exceeding 500 square feet provided it is not occupied as a
permanent dwelling.
R303.9.1 Definitions. For the purposes of this section
only, the following definitions apply.
DESIGNATED AREAS are those areas designated by a
county to be an urban growth area in Chapter 36.70A
RCW and those areas designated by the US
Environmental Protection Agency as being in
nonattainment for particulate matter.
SUBSTANTIALLY REMODELED means any
alteration or restoration of a building exceeding 60 percent
of the appraised value of such building within a 12 month
period. For the purpose of this section, the appraised
value is the estimated cost to replace the building and
structure in kind, based on current replacement costs.
R303.9.2 Primary heating source. Primary heating
sources in all new and substantially remodeled buildings in
designated areas shall not be dependent upon wood stoves.
R303.9.3 Solid fuel burning devices. No new or used solid
fuel burning device shall be installed in new or existing
buildings unless such device is United States Environmental
Protection Agency certified or exempt from certification by
the United States Environmental Protection Agency and
conforms with RCW 70.94.011, 70.94.450, 70.94.453, and
70.94.457.
Exceptions:
1. Wood cook stoves.
2. Antique wood heaters manufactured prior to 1940.
(Insert Facing Page 54)
2012 INTERNATIONAL RESIDENTIAL CODE
Effective July 1, 2013
WASHINGTON STATE AMENDMENTS
Effective July 1, 2013
R311.4 Vertical egress. Egress from habitable levels
including habitable attics and basements not provided with
an egress door in accordance with Section R311.2shall be
by ramp in accordance with Section R311.8 or a stairway in
accordance with Section R311.7.
Exception: Stairs or ladders within an individual
dwelling unit used for access to areas of 200 square feet
(18.6 m2) or less, and not containing the primary
bathroom or kitchen.
(Insert Facing Page 60)
2012 INTERNATIONAL RESIDENTIAL CODE
Effective July 1, 2013
WASHINGTON STATE AMENDMENTS
Effective July 1, 2013
R313 Automatic Fire Sprinkler Systems. This section is
not adopted.
(Insert Facing Page 62)
2012 INTERNATIONAL RESIDENTIAL CODE
Effective July 1, 2013
R314.3 Location. Smoke alarms shall be installed in the
following locations:
1. In each sleeping room.
2. Outside each separate sleeping area in the immediate
vicinity of the bedrooms.
3. On each additional story of the dwelling, including
basements and habitable attics but not including crawl
spaces and uninhabitable attics. In dwellings or
dwelling units with split levels and without an
intervening door between the adjacent levels, a smoke
alarm installed on the upper level shall suffice for the
adjacent lower level provided that the lower level is less
than one full story below the upper level.
4. In napping areas in a family home child care.
R314.3.1 Alterations, Repairs and Additions. When
alterations, repairs or additions requiring a permit occur, or
when one or more sleeping rooms are added or created in
existing dwellings, the individual dwelling unit shall be
equipped with smoke alarms as required for new dwellings.
Exceptions:
1. Work involving the exterior surfaces of dwellings,
such as the replacement of roofing or siding, or the
addition or replacement of windows or doors, or the
addition of a porch or deck are exempt from the
requirements of this section.
2. Installation, alteration or repairs of plumbing,
electrical or mechanical systems are exempt from the
requirements of this section. (Insert Facing Page 63)
R315.1 Carbon Monoxide Alarms. For new construction, an
approved carbon monoxide alarm shall be installed outside of
each separate sleeping area in the immediate vicinity of the
bedroom in dwelling units and on each level of the dwelling
and in accordance with the manufacturer’s recommendations.
R315.2 Carbon monoxide detection systems. Carbon
monoxide detection systems that include carbon monoxide
detectors and audible notification appliances, installed and
maintained in accordance with this section for carbon
monoxide alarms and NFPA 720-2012, shall be permitted.
The carbon monoxide detectors shall be listed as complying
with UL 2075. Where a household carbon monoxide detection
system is installed, it shall become a permanent fixture of the
occupancy.
Exception: Where carbon monoxide alarms are installed
meeting the requirements of Section R315.1, compliance
with Section R315.2 is not required.
WASHINGTON STATE AMENDMENTS
Effective July 1, 2013
R315.3 Where required in existing dwellings. Existing
dwellings shall be equipped with carbon monoxide alarms
in accordance with Section R315.1. An inspection will
occur when alterations, repairs or additions requiring a
permit occur, or when one or more sleeping rooms are
added or created.
Exceptions:
1. Work involving only the exterior surfaces of
dwellings, such as the replacement of roofing or
siding, or the addition or replacement of windows
or doors, or the addition of a porch or deck, or
electrical permits, are exempt from the inspection
requirements of this section.
2. Installation, alteration or repairs of nonfuel
burning plumbing or mechanical systems are
exempt from the inspection requirements of this
section.
3. Owner-occupied single-family residences legally
occupied before July 26, 2009. RCW 19.27.530
(2)(b).
R315.4 Alarm requirements. Single station carbon
monoxide alarms shall be listed as complying with UL
2034 and shall be installed in accordance with this code,
NFPA 720-2012 and the manufacturer’s installation
instructions.
(Insert Facing Page 64)
2012 INTERNATIONAL RESIDENTIAL CODE
Effective July 1, 2013
WASHINGTON STATE AMENDMENTS
Effective July 1, 2013
2012 INTERNATIONAL RESIDENTIAL CODE
Effective July 1, 2013
(Insert Facing Page 69)
R322.2.1 Elevation Requirements. 1. Buildings and structures in flood hazard areas not
designated as Coastal A Zones shall have the lowest
floor elevated to or above the design flood elevation, or
a greater elevation as designated by local ordinance.
2. Buildings and structures in flood hazard areas
designated as Coastal A Zones shall have the lowest
floors elevated to or above the base flood elevation plus
1 foot (305 mm), or to the design flood elevation,
whichever is higher.
3. In areas of shallow flooding (AO Zones), buildings and
structures shall have the lowest floor (including
basement) elevated at least as high above the highest
adjacent grade as the depth number specified in feet on
the FIRM, or at least 2 feet (610 mm)if a depth number
is not specified.
4. Basement floors that are below grade on all sides shall
be elevated to or above the design flood elevation.
Exception: Enclosed areas below the design flood
elevation, including basements whose floors are not
below grade on all sides, shall meet the requirements
of Section R322.2.2.
WASHINGTON STATE AMENDMENTS
Effective July 1, 2013
2012 INTERNATIONAL RESIDENTIAL CODE
Effective July 1, 2013
(Note: No Section R324)
(Insert Facing Page 71)
SECTION R325 ADULT FAMILY HOMES
R325.1 General. This section shall apply to all newly
constructed adult family homes and all existing single family
homes being converted to adult family homes. This section
shall not apply to those adult family homes licensed by the
State of Washington Department of Social and Health Services
prior to July 1, 2001.
R325.2 Submittal standards. In addition to those
requirements in Section 106.1, the submittal shall identify the
project as a Group R, Division 3 Adult Family Home
occupancy. A floor plan shall be submitted identifying the
means of egress and the components in the means of egress
such as stairs, ramps, platform lifts and elevators. The plans
shall indicate the rooms used for clients and the sleeping room
classification of each room.
R325.3 Sleeping room classification. Each sleeping room in
an adult family home shall be classified as:
1. Type S - Where the means of egress contains stairs,
elevators or platform lifts.
2. Type NS1 - Where one means of egress is at grade level
or a ramp constructed in accordance with R325.9 is
provided.
3. Type NS2 - Where two means of egress are at grade level
or ramps constructed in accordance with R325.9 are
provided.
R325.4 Types of locking devices and door activation.
All bedroom and bathroom doors shall be openable from the
outside when locked.
Every closet shall be readily openable from the inside.
Operable parts of door handles, pulls, latches, locks and
other devices installed in adult family homes shall be operable
with one hand and shall not require tight grasping,
pinching or twisting of the wrist. Pocket doors shall have
graspable hardware available when in the closed or open
position.
The force required to activate operable parts shall be 5.0
pounds (22.2 N) maximum. Required exit doors shall have no
additional locking devices.
Required exit door hardware shall unlock inside and outside
mechanisms when exiting the building allowing reentry into
the adult family home without the use of a key, tool or special
knowledge.
R325.5 Smoke and carbon monoxide alarm requirements.
All adult family homes shall be equipped with smoke and
carbon monoxide alarms installed as required in Sections R314
and R315. Alarms shall be installed in such a manner so that
the detection device warning is audible from all areas of the
dwelling upon activation of a single alarm.
R325.6 Escape windows and doors. Every sleeping room
shall be provided with emergency escape and rescue windows
as required by Section R310. No alternatives to the sill height
such as steps, raised platforms or other devices placed by the
openings will be approved as meeting this requirement.
WASHINGTON STATE AMENDMENTS
Effective July 1, 2013
R325.7 Fire apparatus access roads and water supply for
fire protection. Adult family homes shall be served by fire
apparatus access roads and water supplies meeting the
requirements of the local jurisdiction.
R325.8 Grab bar general requirements. Where facilities are
designated for use by adult family home clients, grab bars for
water closets, bathtubs and shower stalls shall be installed
according to this section.
R325.8.1 Grab bar cross section. Grab bars with a circular
cross section shall have an outside diameter of 1 1/4 inches
minimum and 2 inches maximum. Grab bars with
noncircular cross section shall have a cross section
dimension of 2 inches maximum and a perimeter dimension
of 4 inches minimum and 4 5/8 inches maximum.
R325.8.2 Grab bar installation. Grab bars shall have a
spacing of 1 1/2 inches between the wall and the bar.
Projecting objects, control valves and bathtub or shower stall
enclosure features above, below and at the ends of the grab
bar shall have a clear space of 1 1/2 inches to the grab bar.
Exception: Swing-up grab bars shall not be required to
meet the 1 1/2 inch spacing requirement.
Grabs bars shall have a structural strength of 250 pounds
applied at any point on the grab bar, fastener, mounting
device or supporting structural member. Grab bars shall not
be supported directly by any residential grade fiberglass
bathing or showering unit. Acrylic bars found in bathing
units shall be removed.
Fixed position grab bars, when mounted, shall not rotate,
spin or move and have a graspable surface finish.
R325.8.3 Grab bars at water closets. Water closets shall
have grab bars mounted on both sides. Grab bars can be a
combination of fixed position and swing-up bars. Grab bars
shall meet the requirements of R325.8. Grab bars shall
mount between 33 inches and 36 inches above floor grade.
Centerline distance between grab bars, regardless of type
used, shall be between 25 inches minimum and 30 inches
maximum.
R325.8.3.1 Fixed position grab bars. Fixed position grab
bars shall be a minimum of 36 inches in length and start 12
inches from the rear wall.
R325.8.3.2 Swing-up grab bars. Swing-up grab bars shall
be a minimum of 28 inches in length from the rear wall.
R325.8.4 Grab bars at bathtubs. Horizontal and vertical
grab bars shall meet the requirements of R325.8.
R325.8.4.1 Vertical grab bars. Vertical grab bars shall be
a minimum of 18 inches long and installed at the control end
wall and head end wall. Grab bars shall mount within 4
inches of the exterior of the bath tub edge or within 4 inches
within the bath tub. The bottom end of the bar shall start
between 36 inches and 42 inches above floor grade.
Exception: The required vertical grab bar can be
substituted with a floor to ceiling grab bar meeting the
requirements of R325.8 at the control end and head end
entry points.
R325.8.4.2 Horizontal grab bars. Horizontal grab bars
shall be provided at the control end, head end, and the back
wall within the bathtub area. Grab bars shall be mounted
between 33 inches and 36 inches above floor grade. Control
end and head end grab bars shall be 24 inches minimum in
length. Back wall grab bar shall be 36 inches minimum in
length.
R325.8.5 Grab bars at shower stalls. Where shower stalls
are provided to meet the requirements for bathing facilities,
grab bars shall meet the requirements of R325.8.
Exception: Shower stalls with permanent built-in seats
are not required to have vertical or horizontal grab bars at
the seat end wall. A vertical floor to ceiling grab bar shall
be installed within 4 inches of the exterior of the shower
aligned with the nose of the built-in seat.
R325.8.5.1 Vertical grab bars. Vertical grab bars shall be
18 inches minimum in length and installed at the control end
wall and head end wall. Vertical bars shall be mounted
within 4 inches of the exterior of the shower stall or within 4
inches inside the shower stall. The bottom end of vertical
bars mount between 36 inches and 42 inches above floor
grade.
R325.8.5.2 Horizontal grab bars. Horizontal grab bars
shall be installed on all sides of the shower stall mounted
between 33 inches and 36 inches above the floor grade.
Horizontal grab bars shall be a maximum of 6 inches from
adjacent walls. Horizontal grab bars shall not interfere with
shower control valves.
R325.9 Ramps. All interior and exterior ramps, when
provided, shall be constructed in accordance with Section
R311.8 with a maximum slope of 1 vertical to 12 horizontal.
The exception to R311.8.1 is not allowed for adult family
homes. Handrails shall be installed in accordance with
R325.9.1.
R325.9.1 Handrails for ramps. Handrails shall be installed
on both sides of ramps between the slope of 1 vertical to 12
horizontal and 1 vertical and 20 horizontal in accordance
with R311.8.3.1 through R311.8.3.3.
R325.10 Stair Treads and risers. Stair treads and risers shall
be constructed in accordance with R311.7.4. Handrails shall be
installed in accordance with R325.10.1.
R325.10.1 Handrails for treads and risers. Handrails shall
be installed on both sides of treads and risers numbering
from one riser to multiple risers. Handrails shall be installed
in accordance with R311.7.7.1 through R311.7.7.4.
R325.11 Shower stalls. Where provided to meet the
requirements for bathing facilities, the minimum size of
shower stalls for an adult family home shall be 30 inches deep
by 48 inches long.
(Insert As Page 71a)
2012 INTERNATIONAL RESIDENTIAL CODE
Effective July 1, 2013
SECTION R326 FAMILY HOME CHILD CARE
R326 Family home child care. For family home child care
with more than six children, each floor level used for family
child care purposes shall be served by two remote means of
egress. Exterior exit doors shall be operable from the inside
without the use of keys or any special knowledge or effort.
Basements located more than 4 feet below grade level shall
not be used for family home child care homes unless one of
following conditions exist:
1. Stairways from the basement open directly to the exterior
of the building without entering the first floor; or
2. One of the two required means of egress discharges
directly to the exterior from the basement level, and a
self closing door is installed at the top or bottom of the
interior stair leading to the floor above; or
3. One of the two required means of egress is an operable
window or door, approved for emergency escape or
rescue, that opens directly to a public street, public alley,
yard or exit court; or
4. A residential sprinkler system is provided throughout
the entire building in accordance with NFPA 13D.
Floors located more than 4 feet above grade level shall not
be occupied by children in family home child care.
Exceptions:
1. Use of toilet facilities while under supervision of an
adult staff person.
2. Family home child care may be allowed on the second
story if one of the following conditions exists:
2.1 Stairways from the second story open directly to
the exterior of the building without entering the
first floor; or
2.2 One of the two required means of egress
discharges directly to the exterior from the second
story level, and a self closing door is installed at
the top or bottom of the interior stair leading to
the floor below; or
2.3 A residential sprinkler system is provided
throughout the entire building in accordance with
NFPA 13D.
Every sleeping or napping room in a family home child care
shall have at least one operable window for emergency rescue.
Exception: Sleeping or napping rooms having doors
leading to two separate means of egress, or a door leading
directly to the exterior of the building.
Rooms or spaces containing a commercial-type cooking
kitchen, boiler, maintenance shop, janitor closet, laundry,
woodworking shop, flammable or combustible storage, or
painting operation shall be separated from the family home
child care area by at least one-hour fire-resistive construction.
Exception: A fire-resistive separation shall not be required
where the food preparation kitchen contains only a domestic
cooking range and the preparation of food does not result in
the production of smoke or grease laden vapors.
(Insert As Page 71b)
SECTION R327 PROTECTION AGAINST RADON
R327.1 Protection against radon. The radon control
provisions of Appendix F of this code shall apply to buildings
constructed in High Radon Potential Counties (zone 1)
designated in Table AF101(1). The radon control provisions of
Appendix F of this code shall also apply to all buildings
constructed using the provisions of Section R408.3, Unvented
crawl space compliance method.
SECTION R328 MEZZANINES
R328.1 General. Mezzanines shall comply with Section
R328.
R328.2 Mezzanines. The clear height above and below
mezzanine floor construction shall meet the requirements of
R305.1.
R328.3 Area limitation. The aggregate area of a mezzanine
shall be not greater than one-third of the floor area of the room
or space in which they are located. The enclosed portion of a
room shall not be included in a determination of the floor area
of the room in which the mezzanine is located.
R328.4 Means of egress. The means of egress for mezzanines
shall comply with the applicable provisions of Section R311.
R328.5 Openness. A mezzanine shall be open and
unobstructed to the room in which the mezzanine is located
except for walls not more than 42 inches (1067 mm) in height,
columns and posts.
Exceptions:
1. Mezzanines or portions thereof are not required to be
open to the room in which they are located, provided
that the aggregate floor area of the enclosed space is
not greater than 10 percent of the mezzanine area.
2. Mezzanines that are no more than two stories above
grade plane and equipped throughout with an
automatic sprinkler system in accordance with NFPA
13R, NFPA 13D or Appendix R, and having two or
more means of egress, shall not be required to be
open to the room in which the mezzanine is located.
WASHINGTON STATE AMENDMENTS
Effective July 1, 2013
R403.1.2 Continuous footing in Seismic Design Categories
D0, D1 and D2. The braced wall panels at exterior and interior
walls of buildings located in Seismic Design Categories D0, D1
and D2 shall be supported by continuous footings. All required
interior braced wall panels shall be supported on footings at
intervals not exceeding 50 feet (15 240 mm).
TABLE R403.1 MINIMUM WIDTH OF CONCRETE, PRECAST OR MASONRY
FOOTINGS (inches)a
LOAD-BEARING VALUE OF SOIL (psf)
1500 2000 3000 ≥4000
Conventional light-frame construction
1 floorb,c 12 12 12 12
2 floorsb,c 15 12 12 12
3 floorsb,c 23 17 12 12
4-inch brick veneer over light fame or 8-inch hollow concrete masonry
1-story 12 12 12 12
2-story 21 16 12 12
3-story 32 24 16 12
8-inch solid or fully grouted masonry
1-story 16 12 12 12
2-story 29 21 14 12
3-story 42 32 21 16
For SI: 1 inch = 25.4 mm, 1 pound per square foot = 0.0479kPa.
a. Where minimum footing width is 12 inches, use of a single wythe of solid or fully grouted 12-inch nominal concrete masonry units is
permitted.
b. Represents the number of floors supported.
c. Footings shall be permitted to support a roof in addition to the stipulated number of floors. Footings supporting a roof only shall be
as required for supporting one floor.
(Insert Facing Page 78)
2012 INTERNATIONAL RESIDENTIAL CODE
Effective July 1, 2013
WASHINGTON STATE AMENDMENTS
Effective July 1, 2013
R404.1.2.2 Reinforcement for foundation walls. Concrete foundation walls shall be laterally supported at the
top except where permitted in R404.1.2.2.1 and
R404.1.2.2.2, and at the bottom where required elsewhere
in this code. Horizontal reinforcement shall be provided in
accordance with Table R404.1.2(1). Vertical reinforcement
shall be provided in accordance with Table R404.1.2(2),
R404.1.2(3), R404.1.2(4), R404.1.2(5), R404.1.2(6),
R404.1.2(7) or R404.1.2(8). Vertical reinforcement for flat
basement walls retaining 4 feet (1,219 mm) or more of
unbalanced backfill is permitted to be determined in
accordance with Table R404.1.2(9). For basement walls
supporting above-grade concrete walls, vertical
reinforcement shall be the greater of that required by Tables
R404.1.2(2) through R404.1.2(8) or by Section 611.6 for
the above-grade wall. In buildings assigned to Seismic
Design Category D0, D1 or D2, concrete foundation walls
shall also comply with Section R404.1.4.2.
(Insert Facing Page 96)
2012 INTERNATIONAL RESIDENTIAL CODE
Effective July 1, 2013
WASHINGTON STATE AMENDMENTS
Effective July 1, 2013
R404.4 Retaining walls. Retaining walls not supporting a
structure that are not laterally supported at the top and that
retain in excess of 24 inches (610 mm) of unbalanced fill
shall be designed to ensure stability against overturning,
sliding, excessive foundation pressure and water uplift.
Retaining walls shall be designed for a safety factor of 1.5
against lateral sliding and overturning.
(Insert Facing Page 108)
2012 INTERNATIONAL RESIDENTIAL CODE
Effective July 1, 2013
WASHINGTON STATE AMENDMENTS
Effective July 1, 2013
2012 INTERNATIONAL RESIDENTIAL CODE
Effective July 1, 2013
R408.1 Ventilation. The under-floor space between the
bottom of the floor joists and the earth under any building
(except space occupied by a basement) shall have
ventilation openings through foundation walls or exterior
walls.
R408.2 Openings for under-floor ventilation. The
minimum net area of ventilation openings shall not be less
than 1 square foot (0.0929 m2) for each 300 square feet (28
m2) of under-floor area. Required openings shall be evenly
placed to provide cross ventilation of the space except one
side of the building shall be permitted to have no ventilation
openings. Ventilation openings shall be covered for their
height and width with any of the following materials
provided that the least dimension of the covering shall not
exceed 1/4 inch (6.4 mm):
(Insert Facing Page 111)
1. Perforated sheet metal plates not less than 0.070 inch
(1.8 mm) thick.
2. Expanded sheet metal plates not less than 0.047 inch
(1.2 mm) thick.
3. Cast-iron grill or grating.
4. Extruded load-bearing brick vents.
5. Hardware cloth of 0.035 inch (0.89 mm) wire or
heavier.
6. Corrosion-resistant wire mesh, with the least
dimension being 1/8 inch (3.2 mm).
Exception: The total area of ventilation openings shall
be permitted to be reduced to 1/1,500 of the under-
floor area where the ground surface is covered with an
approved Class I vapor retarder material and the
required openings are placed to provide cross
ventilation of the space. The installation of operable
louvers shall not be prohibited. If the installed
ventilation is less than 1/300, or if operable louvers are
installed, a radon vent shall be installed to originate
from a point between the ground cover and soil. The
radon vent shall be installed in accordance with the
requirements of Appendix F (Radon) of this code.
R408.3 Unvented crawl space. Ventilation openings in
under-floor spaces specified in Sections R408.1 and R408.2
shall not be required where:
1. Exposed earth is covered with a continuous Class I
vapor retarder. Joints of the vapor retarder shall
overlap by 6 inches (152 mm) and shall be sealed or
taped. The edges of the vapor retarder shall extend at
least 6 inches (152 mm) up the stem wall and shall
be attached and sealed to the stem wall; and a radon
system shall be installed that meets the requirements
of Appendix F (Radon) of this code.
2. Continuously operated mechanical exhaust
ventilation is provided at a rate equal to 1 cubic foot
per minute (0.47 L/s) for each 50 square feet (4.7 m2)
of crawlspace floor area. Exhaust ventilation shall
terminate to the exterior.
Exception: Plenum in existing structures
complying with Section M1601.5, if under-floor
space is used as a plenum.
WASHINGTON STATE AMENDMENTS
Effective July 1, 2013
2012 INTERNATIONAL RESIDENTIAL CODE
Effective July 1, 2013
R501.3 Fire protection of floors. Floor assemblies, not
required elsewhere in this code to be fire-resistance rated,
shall be provided with a 1/2-inch (12.7 mm) gypsum
wallboard membrane, 5/8-inch (16 mm) wood structural
panel membrane, or equivalent on the underside of the floor
framing member.
Exceptions:
1. Floor assemblies located directly over a space
protected by an automatic sprinkler system in
accordance with Section P2904, NFPA 13D, or
other approved equivalent sprinkler system.
2. Floor assemblies located directly over a crawl
space not intended for storage or fuel-fired
appliances.
3. Portions of floor assemblies can be unprotected
when complying with the following:
3.1. The aggregate area of the unprotected
portions shall not exceed 80 square feet per
story.
3.2. Fire blocking in accordance with Section
R302.11.1 shall be installed along the
perimeter of the unprotected portion to
separate the unprotected portion from the
remainder of the floor assembly.
4. Wood floor assemblies using dimensional lumber
or structural composite lumber with a cross
sectional area equal to or greater than 2-inch by
10-inch nominal dimension, or other approved
floor assemblies demonstrating equivalent fire
performance.
(Insert Facing Page 113)
WASHINGTON STATE AMENDMENTS
Effective July 1, 2013
R507.2.2 Alternate deck ledger connections. Deck ledger
connections not conforming to Table R507.2 shall be
attached with approved fasteners having equivalent
withdrawal capacity or be designed in accordance with
accepted engineering practice. Girders supporting deck
joists shall not be supported on deck ledgers or band joists.
Deck ledgers shall not be supported on stone or masonry
veneer.
R507.2.3 Deck lateral load connections. The lateral load
connection required by Section R507.1 shall be permitted to
be in accordance with Figure R507.2.3. Where the lateral
load connection is provided in accordance with Figure
R507.2.3(1), hold-down tension devices shall be installed in
not less than two locations per deck, and each device shall
have an allowable stress design capacity of not less than
1500 pounds (6672 N).
Exceptions:
1. Decks not more than 30 inches above grade at any
point may be unattached.
2. Where a new deck is being added to an existing
structure, the lateral load connection required by
Section R507.1 shall be permitted to be in
accordance with Figure R507.2.3(2).
Figure R507.2.3(2)
(Insert Facing Page 146)
2012 INTERNATIONAL RESIDENTIAL CODE
Effective July 1, 2013
TABLE 507.2.1 PLACEMENT OF LAG SCREWS AND BOLTS IN DECK LEDGERS AND BAND JOISTS
MINIMUM END AND EDGE DISTANCES AND SPACING BETWEEN ROWS
TOP EDGE BOTTOM EDGE ENDS ROW SPACING
Ledgera 2 inchesd 3/4 inch 2 inchesb 1 5/8 inchesb
Band Joistc 3/4 inch 2 inchese 2 inchesb 1 5/8 inchesb
For SI: 1 inch .= 25.4 mm
a. Lag screws or bolts shall be staggered from the top to the bottom along the horizontal run of the deck ledger in accordance with
Figure R507.2.1(1).
b. Maximum 5 inches.
c. For engineered rim joists, the manufacturer's recommendations shall govern.
d. The minimum distance from bottom row of lag screws to the top edge of the ledger shall be in accordance with Figure R507.2.1(1).
e. The 2 inches may be reduced to 3/4 inch when the band joist is directly supported by a mudsill, a header or by double top wall plates
(Insert Facing Page 147)
WASHINGTON STATE AMENDMENTS
Effective July 1, 2013
R602.9 Foundation cripple walls. Foundation cripple walls
shall be framed of studs not smaller than the studding above.
When exceeding 4 feet (1219 mm) in height, such walls shall
be framed of studs having the size required for an additional
story.
Cripple walls supporting bearing walls or exterior walls or
interior braced wall panels as required in Section R403.1.2 and
R602.10.9.1 with a stud height less than 14
inches (365 mm) shall be continuously sheathed on one side
with wood structural panels fastened to both the top and
bottom plates in accordance with Table R602.3(1), or the
cripple walls shall be constructed of solid blocking.
All cripple walls shall be supported on continuous footings
or foundations.
Exception: Footings supporting cripple walls used to
support interior braced wall panels as required in Sections
R403.1.2 and R602.10.9.1 shall be continuous for the
required length of the cripple wall and constructed beyond
the cripple wall for a minimum distance of 4 inches and a
maximum distance of the footing thickness. The footings
extension is not required at intersections with other
footings.
(Insert Facing Page 158)
2012 INTERNATIONAL RESIDENTIAL CODE
Effective July 1, 2013
WASHINGTON STATE AMENDMENTS
Effective July 1, 2013
2012 INTERNATIONAL RESIDENTIAL CODE
Effective July 1, 2013
R602.10.11 Cripple wall bracing. Cripple walls shall be
constructed in accordance with Section R602.9 and braced
in accordance with this section. Cripple walls supporting
bearing walls or exterior walls or interior braced wall
panels as required in Section R403.1.2 shall be braced with
the length and method of bracing used for the wall above in
accordance with Tables R602.10.3(1) and R602.10.3(3),
and the applicable adjustment factors in Table R602.10.3(2)
or R602.10.3(4), respectively, except the length of the
cripple wall bracing shall be multiplied by a factor of 1.15.
The distance between adjacent edges of braced wall panels
shall be reduced from 20 feet (6096 mm) to 14 feet (4267
mm).
(Insert Facing Page 189)
R602.10.11.2 Cripple wall bracing for Seismic Design
Category D2. In Seismic Design Category D2, cripple
walls supporting bearing walls or exterior walls or interior
braced wall panels as required in Section R403.1.2 shall be
braced in accordance with Tables R602.10.3(3) and
R602.10.3(4).
WASHINGTON STATE AMENDMENTS
Effective July 1, 2013
2012 INTERNATIONAL RESIDENTIAL CODE
Effective July 1, 2013
R612.3 Testing and labeling. Exterior windows and
sliding doors shall be tested by an approved independent
laboratory, and bear a label identifying manufacturer,
performance characteristics and approved inspection
agency to indicate compliance with AAMA/WDMA/CSA
101/I.S.2/A440. Exterior side-hinged doors shall be tested
and labeled as conforming to AAMA/WDMA/CSA
101/I.S.2/A440 or comply with Section R612.5.
Exceptions:
1. Decorative glazed openings.
2. Custom exterior windows and doors manufactured
by a small business shall be exempt from all
testing requirements in Section R612 provided
they meet the applicable provisions of Chapter 24
of the International Building Code.
(Insert Facing Page 347)
WASHINGTON STATE AMENDMENTS
Effective July 1, 2013
R702.5 Other finishes. Wood veneer paneling and
hardboard paneling shall be placed on wood or cold-formed
steel framing spaced not more than 16 inches (406 mm) on
center. Wood veneer and hardboard paneling less than 1/4-
inch (6 mm) nominal thickness shall not have less than a
3/8-inch (10 mm) gypsum board backer. Wood veneer
paneling not less than 1/4-inch (6 mm) nominal thickness
shall conform to ANSI/HPVA HP-1. Hardboard paneling
shall conform to CPA/AHA A135.5. All structural panel
components within the conditioned space such as plywood,
particle board, wafer board and oriented strand board shall
be identified as "EXPOSURE 1," "EXTERIOR" or "HUD-
APPROVED."
(Insert Facing Page 362)
2012 INTERNATIONAL RESIDENTIAL CODE
Effective July 1, 2013
(Insert Facing Page 363)
R703.1.1 Water resistance. The exterior wall envelope shall
be designed and constructed in a manner that prevents the
accumulation of water within the wall assembly by providing a
water-resistant barrier behind the exterior veneer as required
by Section R703.2 and a means of draining water that enters
the assembly to the exterior. Protection against condensation in
the exterior wall assembly shall be provided in accordance
with Section R702.7 of this code.
Exceptions:
1. A weather-resistant exterior wall envelope shall not
be required over concrete or masonry walls designed
in accordance with Chapter 6 and flashed according
to Section R703.7 or R703.8.
2. Compliance with the requirements for a means of
drainage, and the requirements of Section R703.2 and
R703.8, shall not be required for an exterior wall
envelope that has been demonstrated to resist wind-
driven rain through testing of the exterior wall
envelope, including joints, penetrations and
intersections with dissimilar materials, in accordance
with ASTM E 331 under the following conditions:
2.1. Exterior wall envelope test assemblies shall
include at least one opening, one control
joint, one wall/eave interface and one wall
sill. All tested openings and penetrations
shall be representative of the intended end-
use configuration.
2.2. Exterior wall envelope test assemblies shall
be at least 4 feet (1219 mm) by 8 feet (2438
mm) in size.
2.3. Exterior wall assemblies shall be tested at a
minimum differential pressure of 6.24
pounds per square foot (299Pa).
2.4. Exterior wall envelope assemblies shall be
subjected to a minimum test exposure
duration of 2 hours.
The exterior wall envelope design shall be considered
to resist wind-driven rain where the results of testing
indicate that water did not penetrate: Control joints in
the exterior wall envelope; joints at the perimeter of
opening penetration; or intersections of terminations
with dissimilar materials.
3. The requirement for a means of drainage shall not be
construed to mean an air space cavity under the
exterior cladding for an exterior wall clad with panel
or lapped siding made of plywood, engineered wood,
hardboard, or fiber cement. A water-resistive barrier
as required by Section R703.2 and Table R703.4 will
be required on exterior walls.
WASHINGTON STATE AMENDMENTS
Effective July 1, 2013
2012 INTERNATIONAL RESIDENTIAL CODE
Effective July 1, 2013
R703.8 Flashing. Approved corrosion-resistant flashing
shall be applied shingle-fashion in a manner to prevent
entry of water into the wall cavity or penetration of water to
the building structure framing components. Self-adhered
membranes used as flashing shall comply with AAMA 711.
The flashing shall extend to the surface of the exterior wall
finish. Approved corrosion-resistant flashing shall be
installed at all of the following locations:
1. Exterior window and door openings. Flashing at
exterior window and door openings shall extend to
the surface of the exterior wall finish or to the water
resistive barrier for subsequent drainage. (Insert Facing Page 373)
2. At the intersection of chimneys or other masonry
construction with frame or stucco walls, with
projecting lips on both sides under stucco copings.
3. Under and at the ends of masonry, wood or metal
copings and sills.
4. Continuously above all projecting wood trim.
5. Where exterior porches, decks or stairs attach to a
wall or floor assembly of wood-frame construction.
6. At wall and roof intersections.
7. At built-in gutters.
WASHINGTON STATE AMENDMENTS
Effective July 1, 2013
2012 INTERNATIONAL RESIDENTIAL CODE
Effective July 1, 2013
(Insert Facing Page 439)
R903.4.1 Secondary (emergency overflow) drains or
scuppers. Where roof drains are required, secondary
emergency overflow drains or scuppers shall be provided
where the roof perimeter construction extends above the
roof in such a manner that water will be entrapped if the
primary drains allow buildup or any reason. Overflow
drains having the same size as the roof drains shall be
installed with the inlet flow line located 2 inches (51 mm)
above the low point of the roof, or overflow scuppers
having three times the size of the roof drains and having a
minimum opening height of 4 inches (102 mm) shall be
installed in the adjacent parapet walls with the inlet flow
located 2 inches (51 mm) above the low point of the roof
served. The installation and sizing of overflow drains,
leaders and conductors shall comply with the plumbing
code.
Overflow drains shall discharge to an approved location.
WASHINGTON STATE AMENDMENTS
Effective July 1, 2013
2012 INTERNATIONAL RESIDENTIAL CODE
Effective July 1, 2013
(Insert Facing Page 453)
R1001.7.1 Damper. Masonry fireplaces shall be equipped
with a ferrous metal damper located at least 8 inches (203
mm) above the top of the fireplace opening. Dampers shall
be installed in the fireplace or the chimney venting the
fireplace, and shall be operable from the room containing
the fireplace.
Fireplaces shall be provided with each of the following:
1. Tightly fitting flue dampers, operated by a readily
accessible manual or approved automatic control. Exception: Fireplaces with gas logs shall be installed in
accordance with the International Mechanical Code
Section 901, except that the standards for liquefied
petroleum gas installations shall be NFPA 58 (Liquefied
Petroleum Gas Code) and NFPA 54 (National Fuel Gas
Code).
2. An outside source for combustion air ducted into the
firebox. The duct shall be at least 6 square inches, and
shall be provided with an operable outside air duct
damper.
3. Site built fireplaces shall have tight fitting glass or
metal doors, or a flue draft induction fan or as
approved for minimizing back-drafting. Factory built
fireplaces shall use doors listed for the installed
appliance.
WASHINGTON STATE AMENDMENTS
Effective July 1, 2013
2012 INTERNATIONAL RESIDENTIAL CODE
Effective July 1, 2013
R1002.2 Installation. Masonry heaters shall be installed in
accordance with this section and shall be a masonry heater
type approved by the department of ecology. Masonry
heaters shall comply with one of the following:
1. Masonry heaters shall comply with the requirements
of ASTM E 1602; or
2. Masonry heaters shall be listed and labeled in
accordance with UL 1482 and installed in
accordance with the manufacturer's installation
instructions.
R1002.2.1 Combustion air and doors. Masonry heaters
shall be provided with both of the following:
1. Primary combustion air ducted from the outside of
the structure to the appliance.
2. Tight fitting ceramic glass or metal doors. Flue
dampers, when provided, shall have an external
control and when in the closed position shall have a
net free area of not less than 5% of the flue cross
sectional area.
(Insert Facing Page 457)
WASHINGTON STATE AMENDMENTS
Effective July 1, 2013
2012 INTERNATIONAL RESIDENTIAL CODE
Effective July 1, 2013
(Insert Facing Page 461)
R1004.1.1 Emission standards for factory-built
fireplaces. No new or used factory-built fireplace shall be
installed in Washington State unless it is certified and
labeled in accordance with procedures and criteria specified
in ASTM E2558, Standard Test Method for Determining
Particulate Matter Emission from Fires in Low Mass Wood
Burning Fireplaces.
To certify an entire fireplace model line, the internal
assembly shall be tested to determine its particulate matter
emission performance. Retesting and recertifying is
required if the design and construction specifications of the
fireplace model line internal assembly change. Testing for
certification shall be performed by a Washington State
Department of Ecology (DOE) approved and U. S.
Environmental Protection Agency (EPA) accredited
laboratory.
R1004.1.2 Emission standards for certified masonry
and concrete fireplaces. Masonry and concrete fireplace
model lines certified to Washington State Building Code
Standard 31-2 prior to July 1, 2013, may retain certification
provided the design and construction specifications of the
fireplace model line internal assembly do not change.
WASHINGTON STATE AMENDMENTS
Effective July 1, 2013
R1006.2 Solid fuel burning appliances and fireplaces. Solid
fuel burning appliances and fireplaces shall be provided with
tight fitting metal or ceramic glass doors, and:
1. A source from outside the structure of primary
combustion air, connected to the appliance as per
manufacturer's specification. The air inlet shall originate
at a point below the fire box. The duct shall be 4 inches
or greater in diameter, not exceed 20 feet in length, and
be installed as per manufacturer's instructions; or
2. The appliance and manufacturer's recommended
combustion air supply, as an installed unit, shall be
certified by an independent testing laboratory to have
passed Test No. 11-Negative Pressure Test, Section 12.3,
of ULC S627-M1984 "Space Heaters for Use with Solid
Fuels," modified as follows:
Negative pressure of 8 Pascal shall be initially
established with the chamber sealed and the air supply, if
not directly connected to the appliance, closed off.
The air supply if not directly connected to the
appliance, shall then be opened.
The maximum allowable air exchange rate from
chamber leakage and intentional air supply for the unit
(appliance with combustion air supply) in the test
chamber is 3.5 air changes per hour, or 28 cfm (cubic
feet of air per minute), whichever is less.
Exception: Combustion air may be supplied to the
room in which the solid fuel burning appliance is
located in lieu of direct ducting, provided that one of
the following conditions is met:
1. The solid fuel burning appliance is part of a central
heating plant and installed in an unconditioned
space in conformance with the International
Mechanical Code; or
2. The solid fuel burning appliance is installed in
existing construction directly on a concrete floor
or surrounded by masonry materials as in a
fireplace. The combustion air terminus shall be
located as close to the solid fuel burning
appliance as possible and shall be provided with a
barometric damper or equivalent. The combustion
air source shall be specified by the manufacturer
or no less than 4 inches in diameter or the
equivalent in area or as approved.
R1006.4 Passageway. This section is not adopted.
(Insert Facing Page 462)
2012 INTERNATIONAL RESIDENTIAL CODE
Effective July 1, 2013
WASHINGTON STATE AMENDMENTS
Effective July 1, 2013
2012 INTERNATIONAL RESIDENTIAL CODE
Effective July 1, 2013
M1201.1 Scope. The provisions of Chapters 12 through 24
shall regulate the design, installation, maintenance, alteration
and inspection of mechanical systems that are permanently
installed and utilized to provide control of environmental
conditions within buildings. These chapters shall also regulate
those mechanical systems, system components, equipment and
appliances specifically addressed in this code.
Exception: The standards for liquefied petroleum gas
installations shall be the 2011 Edition of NFPA 58
(Liquefied Petroleum Gas Code) and the 2012 Edition of
ANSI Z223.1/NFPA 54 (National Fuel Gas Code).
M1201.3 Construction documents. The plans and
specifications shall show in sufficient detail pertinent data and
features of the materials, equipment and systems as herein
governed including, but not limited to: Design criteria, size
and type of apparatus and equipment, systems and equipment
controls, provisions for combustion air to fuel burning
appliances, and other pertinent data to indicate conformance
with the requirements of this code.
M1201.4 Testing. At the discretion of the building official,
flow testing may be required to verify that the mechanical
system(s) satisfies the requirements of this code. Specific
testing required by other sections of this code shall be
performed. Flow testing may be performed using flow hoods
measuring at the intake or exhaust points of the system, in-line
pitot tube, or pitot-traverse type measurement systems in the
duct, short-term tracer gas measurements, or other means
approved by the building official.
(Insert Facing Page 493)
WASHINGTON STATE AMENDMENTS
Effective July 1, 2013
2012 INTERNATIONAL RESIDENTIAL CODE
Effective July 1, 2013
M1301.2 Identification. Each length of pipe and tubing
and each pipe fitting utilized in a mechanical system shall
bear the identification of the manufacturer.
Exception: The manufacturer identification for fittings
and pipe nipples shall be on each piece or shall be printed
on the fitting or nipple packaging or provided
documentation.
(Insert Facing Page 495)
WASHINGTON STATE AMENDMENTS
Effective July 1, 2013
M1507.1 General. Local exhaust and whole-house
mechanical ventilation systems and equipment shall be
designed in accordance with this section.
(Insert Facing Page 508)
2012 INTERNATIONAL RESIDENTIAL CODE
Effective July 1, 2013
M1507.3 Whole-house mechanical ventilation system.
Whole house mechanical ventilation systems shall be designed
in accordance with Sections M1507.3.1 through M1507.3.7.
M1507.3.1 System design. Each dwelling unit or guestroom
shall be equipped with a ventilation system complying with
Section M1507.3.4, M1507.3.5, M1507.3.6 or M1507.3.7.
Compliance is also permitted to be demonstrated through
compliance with the International Mechanical Code.
M1507.3.2 Control and operation.
1. Location of controls. Controls for all ventilation
systems shall be readily accessible by the occupant.
2. Instructions. Operating instructions for whole-house
ventilation systems shall be provided to the occupant by
the installer of the system.
3. Local exhaust systems. Local exhaust systems shall be
controlled by manual switches, dehumidistats, timers,
or other approved means.
4. Continuous whole-house ventilation systems.
Continuous whole-house ventilation systems shall
operate continuously. Exhaust fans, forced-air system
fans, or supply fans shall be equipped with "fan on" as
override controls. Controls shall be capable of
operating the ventilation system without energizing
other energy-consuming appliances. A label shall be
affixed to the controls that reads "Whole House
Ventilation (see operating instructions)."
5. Intermittent whole-house ventilation systems.
Intermittent whole-house ventilation systems shall
comply with the following:
5.1. They shall be capable of operating intermittently
and continuously.
5.2. They shall have controls capable of operating the
exhaust fans, forced-air system fans, or supply fans
without energizing other energy-consuming
appliances.
5.3. The ventilation rate shall be adjusted according to
the exception in Section 403.8.5.1.
5.4. The system shall be designed so that it can operate
automatically based on the type of control timer
installed.
5.5. The intermittent mechanical ventilation system
shall operate at least one hour out of every four.
5.6. The system shall have a manual control and
automatic control, such as a 24-hour clock timer.
5.7. At the time of final inspection, the automatic
control shall be set to operate the whole-house fan
according to the schedule used to calculate the
whole-house fan sizing.
(Insert Facing Page 509)
5.8. A label shall be affixed to the control that reads
"Whole House Ventilation (see operating
instructions)."
M1507.3.2.1 Operating instructions. Installers shall provide
the manufacturer's installation, operating instructions, and a
whole-house ventilation system operation description.
M1507.3.3 Mechanical ventilation rate. The whole-house
mechanical ventilation system shall provide outdoor air to each
habitable space at a continuous rate of not less than that
determined in accordance with Table M1507.3.3(1).
Exception: The whole-house mechanical ventilation system
is permitted to operate intermittently where the system has
controls that enable operation for not less than 25 percent of
each 4-hour segment and the ventilation rate prescribed in
Table M1507.3.3(1) is multiplied by the factor determined in
accordance with Table M1507.3.3(2).
M1507.3.4 Whole-house ventilation using exhaust fans.
This section establishes minimum prescriptive requirements
for whole-house ventilation systems using exhaust fans. A
system which meets all the requirements of this section shall
be deemed to satisfy the requirements for a whole-house
ventilation system.
M1507.3.4.1 Whole-house ventilation fans. Exhaust fans
providing whole-house ventilation shall have a flow rating at
0.25 inches water gauge as specified in Table M1507.3.3(1).
Manufacturers' fan flow ratings shall be determined according
to HVI 916 or AMCA 210.
M1507.3.4.2 Fan noise. Whole-house fans located 4 feet or
less from the interior grille shall have a sone rating of 1.0 or
less measured at 0.1 inches water gauge. Manufacturer's noise
ratings shall be determined as per HVI 915 (March 2009).
Remotely mounted fans shall be acoustically isolated from the
structural elements of the building and from attached duct
work using insulated flexible duct or other approved material.
M1507.3.4.3 Fan controls. The whole-house ventilation fan
shall meet the requirements of Section M1507.3.2 and
M1507.3.2.1.
M1507.3.4.4 Outdoor air inlets. Outdoor air shall be
distributed to each habitable space by individual outdoor air
inlets. Where outdoor air supplies are separated from exhaust
points by doors, provisions shall be made to ensure air flow by
installation of distribution ducts, undercutting doors,
installation of grilles, transoms, or similar means. Doors shall
be undercut to a minimum of 1/2 inch above the surface of the
finish floor covering.
Individual room outdoor air inlets shall:
1. Have controllable and secure openings;
2. Be sleeved or otherwise designed so as not to
compromise the thermal properties of the wall or
window in which they are placed;
3. Provide not less than 4 square inches of net free area of
opening for each habitable space. Any inlet or
combination of inlets which provide 10 cfm at 10
Pascals are deemed equivalent to 4 square inches net
free area.
WASHINGTON STATE AMENDMENTS
Effective July 1, 2013
Inlets shall be screened or otherwise protected from entry by
leaves or other material. Outdoor air inlets shall be located so
as not to take air from the following areas:
1. Closer than 10 feet from an appliance vent outlet,
unless such vent outlet is 3 feet above the outdoor air
inlet.
2. Where it will pick up objectionable odors, fumes or
flammable vapors.
3. A hazardous or unsanitary location.
4. A room or space having any fuel-burning appliances
therein.
5. Closer than 10 feet from a vent opening of a plumbing
drainage system unless the vent opening is at least 3
feet above the air inlet.
6. Attic, crawl spaces, or garages.
M1507.3.5 Whole-house ventilation integrated with a
forced-air system. This section establishes minimum
prescriptive requirements for whole-house ventilation systems
integrated with forced-air ventilation systems. A system which
meets all the requirements of this section shall be deemed to
satisfy the requirements for a whole-house ventilation system.
M1507.3.5.1 Integrated whole-house ventilation systems.
Integrated whole-house ventilation systems shall provide
outdoor air at the rate calculated using Section M1507.3.3.
Integrated forced-air ventilation systems shall distribute
outdoor air to each habitable space through the forced-air
system ducts. Integrated forced-air ventilation systems shall
have an outdoor air inlet duct connecting a terminal element
on the outside of the building to the return air plenum of the
forced-air system, at a point within 4 feet upstream of the air
handler. The outdoor air inlet duct connection to the return
air stream shall be located upstream of the forced-air system
blower and shall not be connected directly into a furnace
cabinet to prevent thermal shock to the heat exchanger. The
system will be equipped with a motorized damper connected
to the automatic ventilation control as specified in Section
M1507.3.2. The required flow rate shall be verified by field
testing with a flow hood or a flow measuring station.
M1507.3.5.2 Ventilation duct insulation. All supply ducts
in the conditioned space shall be insulated to a minimum of
R-4.
M1507.3.5.3 Outdoor air inlets. Inlets shall be screened or
otherwise protected from entry by leaves or other material.
Outdoor air inlets shall be located so as not to take air from
the following areas:
1. Closer than 10 feet from an appliance vent outlet,
unless such vent outlet is 3 feet above the outdoor air
inlet.
2. Where it will pick up objectionable odors, fumes or
flammable vapors.
3. A hazardous or unsanitary location.
4. A room or space having any fuel-burning appliances
therein.
5. Closer than 10 feet from a vent opening of a
plumbing drainage system unless the vent opening is
at least 3 feet above the air inlet.
6. Attic, crawl spaces, or garages.
M1507.3.6 Whole-house ventilation using a supply fan.
This section establishes minimum prescriptive requirements
for whole-house ventilation systems using an inline supply fan.
A system which meets all the requirements of this section shall
be deemed to satisfy the requirements for a whole-house
ventilation system.
M1507.3.6.1 Outdoor air. Supply fan ventilation systems
shall distribute outdoor air to each habitable space through
the forced-air system ducts or through dedicated ducts to
each habitable space. Supply fans shall have the capacity to
provide the amount of outdoor air specified in Table
M1507.3.3(1) at 0.40 inches water gauge as per HVI 916.
The outdoor air must be filtered before it is delivered to
habitable spaces. The filter may be located at the intake
device, in line with the fan, or, in the case of a connection to
the return plenum of the air handler, using the furnace filter.
An outdoor air inlet shall be connected to either the supply
or return air stream.
M1507.3.6.2 Ducts. An outdoor air inlet duct connection to
the supply air stream shall be located downstream of the
forced-air system blower. An outdoor air inlet duct
connection to the return air stream shall be located at least 4
feet upstream of the forced-air system blower and its filter.
Neither type of duct shall be connected directly into a
furnace cabinet to prevent thermal shock to the heat
exchanger. The outdoor air inlet duct shall be prescriptively
sized in accordance with Table M1507.3.6.2. The terminal
element on the outside of the building shall be sized 2 inches
in diameter larger than the outdoor air inlet duct.
TABLE M1507.3.6.2 PRESCRIPTIVE SUPPLY FAN DUCT SIZING
Supply Fan Tested CFM at 0.40” w.g.
Specified Volume from
Table M1507.3.3(1)
Minimum Smooth Duct
Diameter
Minimum Flexible Duct
Diameter
50-90 cfm 4 inch 5 inch
90-150 cfm 5 inch 6 inch
150-120 cfm 6 inch 7 inch
250-400 cfm 7 inch 8 inch
M1507.3.6.3 Dampers. The system shall be equipped with
a back-draft damper and one of the following:
1. A calibrated manual volume damper installed and set
to meet the measured flow rates specified in Table
M1507.3.3(1) by field testing with a pressure gauge
and/or following manufacturer's installation
instructions; or
2. A manual volume damper installed and set to meet
the measured flow rates specified in Table
M1507.3.3(1) by field testing with a flow hood or a
flow measuring station; or
(Insert As Page 509a)
2012 INTERNATIONAL RESIDENTIAL CODE
Effective July 1, 2013
3. An automatic flow-regulating device sized to the
specified flow rates in Table M1507.3.3(1) which
provides constant flow over a pressure range of 0.20
to 0.60 inches water gauge.
M1507.3.6.4 Ventilation duct insulation. All supply ducts
in the conditioned space shall be insulated to a minimum of
R-4.
M1507.3.6.5 Outdoor air inlets. Inlets shall be screened or
otherwise protected from entry by leaves or other material.
Outdoor air inlets shall be located so as not to take air from
the following areas:
1. Closer than 10 feet from an appliance vent outlet,
unless such vent outlet is 3 feet above the outdoor air
inlet.
2. Where it will pick up objectionable odors, fumes or
flammable vapors.
3. A hazardous or unsanitary location.
4. A room or space having any fuel-burning appliances
therein.
5. Closer than 10 feet from a vent opening of a
plumbing drainage system unless the vent opening is
at least 3 feet above the air inlet.
6. Attic, crawl spaces, or garages.
M1507.3.7 Whole-house ventilation using a heat recovery
ventilation system. This section establishes minimum
prescriptive requirements for whole-house ventilation using a
heat recovery ventilation system.
M1507.3.7.1 Heat recovery ventilation systems. All duct
work in heat recovery systems shall be sized and installed
per the manufacturer's instructions. System minimum flow
rating shall be not less than that specified in Table
M1507.3.3(1). Heat recovery ventilation systems shall have
a filter on the upstream side of the heat exchanger in both
the intake and exhaust airstreams with a minimum efficiency
rating value (MERV) of 6.
M1507.3.7.2 Ventilation duct insulation. All supply ducts
in the conditioned space installed upstream of the heat
exchanger shall be insulated to a minimum of R-4.
M1507.3.7.3 Outdoor air inlets. Inlets shall be screened or
otherwise protected from entry by leaves or other material.
Outdoor air inlets shall be located so as not to take air from
the following areas:
1. Closer than 10 feet from an appliance vent outlet,
unless such vent outlet is 3 feet above the outdoor air
inlet.
2. Where it will pick up objectionable odors, fumes or
flammable vapors.
3. A hazardous or unsanitary location.
4. A room or space having any fuel-burning appliances
therein.
5. Closer than 10 feet from a vent opening of a
plumbing drainage system unless the vent opening is
at least 3 feet above the air inlet.
6. Attic, crawl spaces, or garages.
(Insert As Page 509b)
M1507.4 Local exhaust. Local exhaust shall be provided in
each kitchen, bathroom, water closet, laundry room, indoor
swimming pool, spa, and other rooms where water vapor or
cooking odor is produced. Local exhaust systems shall be
designed to have the capacity to exhaust the minimum air flow
rate determined in accordance with Table M1507.4.
TABLE M1507.4 MINIMUM REQUIRED LOCAL EXHAUST RATES FOR
ONE- AND TWO-FAMILY DWELLINGS
AREA TO BE EXHAUSTED EXHAUST RATES
Kitchens 100 cfm intermittent or
25 cfm continuous
Bathrooms—toilet rooms
Laundry rooms
Indoor swimming pools &
spas
Mechanical exhaust
capacity of
50 cfm intermittent or
20 cfm continuous
For SI: 1 cubic foot per minute = 0.0004719 m3/s.
M1507.4.1 Local exhaust fans. Exhaust fans providing
local exhaust shall have a minimum fan flow rating not less
than 50 cfm at 0.25 inches water gauge for bathrooms,
laundries, or similar rooms and 100 cfm at 0.25 inches water
gauge for kitchens. Manufacturers' fan flow ratings shall be
determined as per HVI 916 (April 1995) or AMCA 210.
Exception: Where a range hood or down draft exhaust
fan is used to satisfy the local exhaust requirements for
kitchens, the range hood or down draft exhaust shall not
be less than 100 cfm at 0.10 inches water gauge.
M1507.4.2 Local exhaust controls. Local exhaust systems
shall be controlled by manual switches, dehumidistats,
timers, or other approved means. Local exhaust system
controls shall be readily accessible.
WASHINGTON STATE AMENDMENTS
Effective July 1, 2013
2012 INTERNATIONAL RESIDENTIAL CODE
Effective July 1, 2013
M1601.1.1 Above-ground duct systems. Above-ground
duct systems shall conform to the following:
1. Equipment connected to duct systems shall be
designed to limit discharge air temperature to a
maximum of 250°F (121°C).
2. Factory-made air ducts shall be constructed of Class 0
or Class 1 materials as designated in Table
M1601.1.1(1).
3. Fibrous duct construction shall conform to the
SMACNA Fibrous Glass Duct Construction
Standards or NAIMA Fibrous Glass Duct
Construction Standards.
4. Minimum thickness of metal duct material shall be as
listed in Table M1601.1.1(2). Galvanized steel shall
conform to ASTM A 653. Metallic ducts shall be
fabricated in accordance with SMACNA Duct
Construction Standards Metal and Flexible.
5. Use of gypsum products to construct return air ducts
or plenums is permitted, provided that the air
temperature does not exceed 125°F (52°C) and
exposed surfaces are not subject to condensation.
6. Duct systems shall be constructed of materials having
a flame spread index not greater than 200.
7. Stud wall cavities and the spaces between solid floor
joists shall not be used as a duct or an air plenum in
new construction. For existing systems, stud wall
cavities and the spaces between solid floor joists to be
used as air plenums shall comply with the following:
7.1. These cavities or spaces shall not be used as a
plenum for supply air.
7.2. These cavities or spaces shall not be part of a
required fire-resistance-rated assembly. (Insert Facing Page 511)
7.3. Stud wall cavities shall not convey air from
more than one floor level.
7.4. Stud wall cavities and joist-space plenums shall
be isolated from adjacent concealed spaces by
tight-fitting fire blocking in accordance with
Section R602.8.
7.5. Stud wall cavities in the outside walls of
building envelope assemblies shall not be utilized
as air plenums.
WASHINGTON STATE AMENDMENTS
Effective July 1, 2013
2012 INTERNATIONAL RESIDENTIAL CODE
Effective July 1, 2013
M1701.1 Scope. Solid-fuel-burning appliances shall be
provided with combustion air in accordance with the
appliance manufacturer's installation instructions. Oil-fired
appliances shall be provided with combustion air in
accordance with NFPA 31. The methods of providing
combustion air in this chapter do not apply to fireplaces,
fireplace stoves and direct-vent appliances. The
requirements for combustion and dilution air for gas-fired
appliances shall be in accordance with Chapter 24.
Fireplaces shall comply with Chapter 10.
(Insert Facing Page 515)
WASHINGTON STATE AMENDMENTS
Effective July 1, 2013
2012 INTERNATIONAL RESIDENTIAL CODE
Effective July 1, 2013
Informational Note: Boilers and pressure vessels are
regulated by Chapter 70.79 RCW and Chapter 296-104
WAC in addition to the requirements of this code.
(Insert Facing Page 523)
WASHINGTON STATE AMENDMENTS
Effective July 1, 2013
2012 INTERNATIONAL RESIDENTIAL CODE
Effective July 1, 2013
Chapter 44
Referenced Standards
Add the following standard:
NFPA National Fire Protection Association
1 Batterymarch Park Quincy, MA 02269
Standard
reference number Title
Referenced
in code section number
720-12 Standard for the installation of Carbon Monoxide (CO) Detectors and Warning Equipment .................................................... R315.4
(Insert Facing Page 781)
WASHINGTON STATE AMENDMENTS
Effective July 1, 2013
2012 INTERNATIONAL RESIDENTIAL CODE
Effective July 1, 2013
AF101.1 General. This appendix contains requirements
for new construction in jurisdictions where radon-resistant
construction is required.
Inclusion of this appendix by jurisdictions shall be
required in high radon potential counties as determined in
Figure AF101 and as listed in Table AF101(1).
Unvented crawl spaces are not permitted in any high
radon potential county. In other areas, requirements of this
appendix apply to any structure constructed with unvented
crawl spaces as specified in R408.3.
AF103.1 General. The following construction techniques
are intended to resist radon entry and prepare the building
for post-construction radon mitigation, if necessary (see
Figure AF102). These techniques are required in high radon
potential counties designated in Table AF101(1).
(Insert Facing Page 821)
WASHINGTON STATE AMENDMENTS
Effective July 1, 2013
WAC 51-51-60105
APPENDIX R
DWELLING UNIT FIRE SPRINKLER SYSTEMS
The design and installation of residential fire sprinkler
systems shall be in accordance with the 2012 International
Residential Code Section P2904 Dwelling Unit Fire
Sprinkler Systems.
(Insert as Page 890a)
2012 INTERNATIONAL RESIDENTIAL CODE
Effective July 1, 2013
WASHINGTON STATE AMENDMENTS
Effective July 1, 2013
WAC 51-51-60107
APPENDIX S
FIRE SPRINKLERS The provisions contained in this appendix are not mandatory unless specifically
referenced in the adopting ordinance.
AS107.1 Fire sprinklers. An approved automatic fire
sprinkler system shall be installed in new one-family and
two-family dwellings and townhouses in accordance with
Appendix R.
(Insert as Page 890b)
2012 INTERNATIONAL RESIDENTIAL CODE
Effective July 1, 2013